1. Field of the Invention
This invention relates in general to the removal of residual polyethers from aqueous waste streams so that such streams can be disposed of in an environmentally safe manner. In another aspect, this invention is directed to the removal of polyethers from aqueous waste streams by adsorbance of the polyethers on an inert substrate and destruction of the residual polyethers by combustion. In a further aspect, this invention relates to a process wherein the inert substrate can be regenerated and recycled for further use.
2. Description of the Prior Art
Alkylene ether polymers are not considered to be particularly hazardous and accordingly, their removal from aqueous solutions has not received much attention in the past. However, it appears from commercial and industrial operations which use such polymers, as well as due to the ever changing regulations of the Environmental Protection Agency, that the removal of such materials from aqueous solutions is becoming a problem of increasing importance. While the removal of polyethers which are present in aqueous solutions in relatively high concentrations can be accomplished economically by well known methods, the removal of trace amounts from waste streams to comply with environmental regulations presents an additional problem. The processing of large volumes of liquid waste streams to remove only minor amounts of polyether can be expensive and time consuming.
Prior to the present invention, a variety of techniques were available for the separation of alkylene ether polymers from aqeuous solutions include cloud point precipitation, chemical precipitation, ultrafiltration, adsorption on solids, biodegradation, and the like. Depending upon the concentration of the polyether in solution, different techniques or a combination of techniques may be necessary to remove the polymer. For example, in the high concentration range (5-10%), cloud point precipitation may be effective to reduce the polymer to a fraction of a percent. Adsorption, on the other hand, may be effective in the low concentration range to reduce the polyether to ppm levels. Chemical precipitation involves the introduction of another reagent and hence, the effect of residual amounts of the additive in the waste stream should be considered.
Ultrafiltration is becoming a widely accepted technique for the separation of macromolecules and ultrafine solids. Membrane fouling, low filtration rate, and the like are among the problems involved in U.F. In biodegradation, the fate of the microorganism and of the degraded produce should be considered. In short, all the techniques have definite advantages, but associated limitations. Yet another factor to take into consideration while selecting a particular technique is the subsequent disposal/separation/regeneration problem.
Accordingly, one or more of the following objects will be achieved by the practice of the present invention. It is an object of this invention to provide a method for the removal of residual polyethers from aqueous waste streams in an environmentally safe manner. Another object of this invention is to provide a method for the removal of polyethers from waste streams wherein essentially all of the polyether is adsorbed from the waste stream in one operation. A further object of the present invention is to provide a method wherein residual polyethers are adsorbed on an inert substrate. Another object is to provide a method wherein the adsorbed polyethers are removed from the substrate as carbon dioxide and water. A still further object is to provide a process for regenerating and recycling the substrate for use in further adsorption of polyethers. Another object is to provide a continuous process for removing residual polyethers from aqueous waste streams wherein the adsorbent is regenerated and recycled in an environmentally safe manner. These, and other, objects will readily become apparent to those skilled in the art in light of the teachings herein set forth.